Chitin, white, horny substance found in the outer skeleton of insects, crabs, and lobsters and in the internal structures of other invertebrates. It is a polysaccharide consisting of units of the amino sugar glucosamine. As a by-product of crustacean processing, chitin is used as a flocculating agent for waste water, a wound-healing agent, a thickener and stabilizer for foods and pharmaceuticals, an ion-exchange resin, a membrane for chromatography and electrodialysis, a binder for dyes, fabrics, and adhesives, and a sizing and strengthening agent for paper. . Chitin is observed within the exoskeletons of bugs, the cell walls of fungi, and sure hard structures in invertebrates and fish. In terms of abundance, chitin is 2d to handiest cellulose. inside the biosphere, over 1 billion heaps of chitin are synthesized each 12 months through organisms. This extremely flexible molecule can form solid structures on its own as in insect wings, or can integrate with other additives like calcium carbonate to make even more potent substances like the shell of a clam.Like cellulose, no vertebrate animals can digest chitin on their own. Animals that eat a diet of insects regularly have symbiotic bacteria and protozoa that can ruin down the fibrous chitin into the glucose molecules that compose it.